Means for preventing ice formation in jet propulsion and gas turbine engines



4, 1953 w. M CANN MEANS FOR PREVENTING ICE FORMATION IN JET PROPULSION AND GAS TURBINE ENGINES Filed June 24, 1946 Z] r It'll/lam 1 #06000 Patented Aug. 4, 1953 2,647,366' e MEANS FOR PREVENTINGICE: FORMATION IN JET PROPULSION ENGINES AND GAS TURBINE William 'J. McCann, BereafOhio Application June 24, 1946, Serial No. 678.758 2 Claims. (c1. (in-35.6) (Grantham-ewe 35, us. Code (1952),

1 This invention relates to a means for preventing ice formation in jet propulsion and gas turbine engines and particularly to deicing and controlling the air supply at the inlet;

The basic elements of both the turbo-jet and propeller-jet systems may take a number of forms. However, the two systems have in common the characteristic of requiring large quantities of air. Therefore, when an aircraft powered with either of these types of propulsion system flies through atmospheric conditions favorable to the formation of ice, there is a strong possibility, in the light'of the performance of conventional aircraft engines operating under similar conditions, that quantities of ice will form at the entrance to the power plant intake systems, within the duct leading to the power plant and at the compressor entrance. It would be expected that this ice formation would greatly impair the performance of the power plant by reducing the amount of air admitted to the compressor and it is entirely possible that the entrance of ice particles into the compressor would destroy the system and make it inoperative. It is desirable therefore, that means for preventing ice in turbo-jet engines and in turbopropeller engines be made available in the immediate future.

, sec. 266), a

Also, a need for providing a means for controlling air flow through power systems of this type hasbeen demonstrated by tests and by flight experience. If, as a result of pilot error or other cause, one of these power systems becomes inoperative in high speed flight, the amount of air flowing through the unit, determined by flight speed and altitude, is obviously much greater than under slow speed or ground starting conditions. Since the combustion chambers are not designed to operate under extremely high rates of air flow, and for other reasons, the pilot may be unable to start the engine in the types of installations that are being made at the present time because the flame would tend to .be blown out by the high velocity air. However, if the means could be provided for reducing the air flow through the unit, the present day starter and ignition system would be adequate to start the unit by allowing a flame to propagate normally.

The object of this invention is to provide means for preventing ice formation in turbo-jet and turbo-propeller engines and for providing control over the quantity of air admitted to the unit in flight.

- control system.-

- 2 Details of the invention are described in connection with the drawing in which Fig. l is a schematic drawing of a turbo-jet engine equipped with the ice prevention and air Fig. 2 is a front view. The drawing shows the power plant 'schematicallyhaving engine air entrance I, nose fairing 2, compressor 3, combustion chamber 4, gas

turbine'5, exhaust fairing 6, and exit nozzle 7. r

The compressor 3 has the rotating vanes there-- of cooperating with the vanes secured on the inside of the casing or engine body. Air coming intothe intake I is compressed by action of the blades and the narrowing passage and forced into the combustion chamber 4. Any suitable means, not shown, is provided for bringme fuel into the combustion chamber, and for starting the compressor, and cobustion process. Gases formed by "the combustion in chamber 4 are forced past vanes 5 which rotate and thereby impart rotary movement to the compressor vanes. The combustiongases flow past'the exhaust fairin; 6 and through exit nozzle 1, imparting for-Q ward thrust to the engine or power plant.

In the present invention; a number of stream lined hollow tubes [4 are placed across the air inletduct either at the entrance to the duct or slightly behind the entrance. Thesetubes are pivoted in any conventional manner to'provide a shutter effect and each tube is provided with either. continuous or intermittent slots. The rotary position of the tubes l4 may be adjusted by the mechanism shown, by movement of the rod 15, which may extend'operatively to the pilots cockpit, as will readiy be understood by those skilled in the art. Heated air is provided for these tubes in a manner to be later described and flows through these slots into the incomin air stream to mix with the intake air and increase its temperature above the point at which ice formation can occur.

An adequate quantity of compressed air is obtained from the compressor by means of compressor air bleed 8 which may be in the form of a peripheral jacket, as shown. Heating air control valve 9 of any suitable design is provided to control the compressed air leading from air bleed 8 into duct l0. Compressed air entering duct I0 is carried rearwardly into heat exchange manifold H where the air is heated due to the high temperatures in exhaust fairing 6. The heated air is then carried to the distributing manifold l3 by means of duct I2 and. then into the hollow streamlined tubes 14- Tubes 4 can be rotated about their axes to reduce or completely stop the flow of air through air inlet I into the engine for starting in flight or to prevent windmilling of the rotor of an inoperative engine in. flight, that is, to prevent the windmillalike rotations of the rotor resulting from the air passing through the compressor blades 3.

It will be apparent that heated air from the" to prevent ice formation within the duct and also to permit a maximum period. of time for mixing the heated air with the incoming airandv thus insuring. complete melting of any large ice or snow particles that enter the duct.

Preliminar calculations indicate that it may be possible to prevent ice formation within the duct system of the types of engines described-,- in this memorandum by having 10 per cent of the mass air flow admitted through the de-icing. system. The heated air would be. supplied: at. temperatures of the order of 350 to 400 F. and the amount of heat requiredjrom. the heat exchanger fl at the main propulsion iet would be comparatively low when. air is bled from the engine. compressor since the compressor discharge air will be approximately 300 F. inmost. power plants.

It is believed, that the leading edge oi the. engine cowling can be suitably de-i'ced. either bymethods already adaptedto present day aircraft or by means of an additional heated air stream which is circulated through a. double wall construction at the cowling leading edge. and permitted to flow back within the nacelle for purposes of ventilating the nacelle and supplying a limited amount of ice protection for the nacell'e back of the leading edge.

Ice can be prevented or eliminated in the. intake duct to the engine, in' the duct, and on a protective screen (if such screen is. used) withoutatfooting the normal use of the. engine even though some loss in both total thrust andefiiciency is anticipated.

The proposed streamlined. struts or tubes IA offer promise of permitting the elimination of; the rather high drag screens that. are used in present engines so as to protect the engine from foreign bodies that may enter the system, particularly during ground handling, takeoff or land- The changes that would have to be made to existing prepuls'wn engines-in order to adapt this system will be relatively minor in nature since it would be necessary to provide only for bleedo'fi ducts at the engine compressor together with suitable Valves at this point so that the de-icing system: can be used only when flight conditions demand such protection.

The invention described herein may be manufactured and used by or for the Government of the States of America for governmental purposes without the payment of any royalties thereon or therefor.

What]: claim 1. In an aircraft power plant, a gas turbine engine having a compressor, combustion equipment in whieh. air from the compressor is heated, and a turbine driven by the heated air, a casing enclosing said power plant. and havingv an. air in-- take at its forward. end communicating with said compressor, said casing. havingv an exhaust region aft of, said turbine, a plurality of hollow tubes having perforations therein. and mounted in said air intalre,v a heat exchanger in said exhaust region, means connected tov the heat exchanger for conducting a quantity of air from said compressor to said heat exchanger in order to heat the quantity of air, an air duct extending from said heat exchanger and terminating at said air inlet, and an air distributing manifold connected to. said tubes and to said air duct for supplying heated air to said tubes.

2. The power plant of claim 1 wherein said. air conducting means comprises a jacket provided peripherally in said casing; and said heat exchangeris arranged peripherally of said exhaust region.

J. MCCANN.

References Cited. in the file of this. patent UNITED STATES PATENTS Number Name Date 1,539,711" Coppus May 26', 192-5 1,977,538 Anderson Oct. 16, 1934 233391629 Fischer Jan. 18, 1944 2,344,835- Stalker Mar. 21, 1944 2,404,275 Clark et al. July 16; 1946 .",42' 1 668' Sammons et' a1. June2l, I949 2t777l8 Gri'fllth Aug. 2, 1949 2,508,288 Owner et al. May 1 6', I950 

